Longitudinal measures are more often used in basic research studies than as social indicators. Indeed, the set of available longitudinal indicators is very small, and many domains have only cross-sectional indicators. Nevertheless, although longitudinal indicators are not common at present, a few examples are available. For example, in the social context of family, work, and child care, the annual report to Congress on Indicators of Welfare Dependence contains a measure of long-term poverty and long-term welfare receipt (U.S. Department of Health and Human Services, 2003). These indicators go beyond reports of poverty or welfare receipt at the time of the interview or during the previous month to assess the number or proportion of the past several years that a family has received welfare or been in poverty.
Long-term poverty is probably the most widely-known longitudinal indicator relevant to families, and long-term poverty has been found to be associated with particularly negative outcomes for children (Duncan et al, 1994; Corcoran et al., 1992), especially young children (Duncan and Brooks-Gunn, 1997).
Another existing longitudinal indicator falls under the realm of youth connections. Consistent participation in extracurricular activities has not been operationalized in a standard way that could be used as an indicator. However, analyses of the National Education Longitudinal Survey (NELS:88) indicate that high school students who consistently reported across three survey interviews in eighth, tenth, and twelfth grades that they participated in an extracurricular activity during their high school years were more likely to attend college, vote, and volunteer for a community or religious organization two years after high school (Zaff, Moore, Papillo and Williams, 2003).
To support a child's learning, achievement and development, their home environment needs to be supportive as they grow up. Despite this, the quality of the home environment is more often assessed at a point in time than over time. However, Moore et al. (2002) examined a number of different ways to measure the cognitive stimulation and warmth available to a child, using data from the National Longitudinal Survey of Youth, 1979 cohort, specifically, the HOME short scale. This measure could be considered an indicator of family functioning. They found that brief scales assessing aspects of the home environment collected regularly over time predict delinquency and PIAT test scores (but not parent-child activities) similarly to or better than a longer cross-sectional measure in multivariate regression analyses. (They also found that a shortened, longitudinal measure of the Behavior Problems Index predict delinquency, PIAT test scores and smoking as well as or better than cross-sectional versions.) Unfortunately, this is the only study we have found that explicitly compared short-term versus long-term duration or exposure, apart from poverty and welfare (Zill et al., 1991).
Another aspect of family functioning that has been studied is long-term maternal depression. Studies have found that long-term depression has more negative implications for child development than shorter-term depression (review by Coiro, 1998, as cited in Ahluwalia et al. 2001).
The presence of other health problems, which could also affect family functioning, is frequently studied in public health research studies. For example, the National Center for Health Statistics tracks the incidence among children of asthma, allergies, learning disabilities, attention deficit hyperactivity disorder (Bloom et al., 2003) and, in the National Health Interview Survey, the incidence among the entire population of limitations in usual activities and limitations in work activities (Schoenborn et al., 2003). Although previous research has typically assessed the incidence of such conditions at single points in time, many of these health problems tend to be chronic, and it would be helpful to know the proportion of a child's life during which a health problem has been experienced. Caring for a disabled or chronically ill child is stressful for families (Smith et al., 2001). And while research is mixed on the academic effects of chronic illness on children, it has been linked with social adjustment problems and depression among children (Sinnema, 1991; Boekaerts and Röder, 1999). Therefore, using longitudinal indicators to assess the presence of health problems over time could be useful.
Another longitudinal measure that taps families' social connections is mobility. Mobility is often assessed with retrospective data. For example, the Census long form questionnaire asks about mobility, assessing whether each person in the household "live[d] in this house or apartment five years ago" as well as the year in which the householder moved to the present address. Mobility affects people directly, as well as geographic areas. For example, some families may move in order to improve their economic well-being or to live in a better home or neighborhood (Schachter, Franklin, and Perry, 2003). However, stability (that is, residence in the same location over a long period of time) can be positive as well, improving residents' social connections with each other, particularly in non-poor neighborhoods (Ross, Reynolds, and Geis, 2000). Residential moves that include school changes have also been linked with school problems for children (Scanlon and Devine, 2001).
While this is not an exhaustive review of longitudinal measures and indicators, it is clear that there are indicators from many domains and that, when they have been measured and studied, long-term and ongoing behavior, attitudes or circumstances are related to family and child well-being. Indeed, cross-sectional measures are in some sense taking advantage of the well-known tendency for long-term behaviors (such as welfare receipt) to be over-represented in cross-sectional data (Bane and Ellwood, 1994). Hence, if a person has a chronic illness or an unhappy marriage, they are quite likely to have that characteristic the day that they participate in a survey or study. Accordingly, many cross-sectional indicators provide a signal of the underlying longer-term condition. While it might be preferable to assess the duration of a behavior, attitude or circumstance directly, doing so needs to be considered relative to the feasibility and cost of obtaining longitudinal data in a given instance.